Sandwich sheets, which usually have two outer metal cover sheets and at least one nonmetallic core layer arranged between the metal cover layers, said nonmetallic core layer preferably consisting of thermoplastic material, are used in order to provide composite sheet parts which have properties that are at least mutually exclusive in a sheet made of solid material. A sandwich sheet, in spite of its low weight, for example, allows locally very good stiffness and can simultaneously provide very good sound insulation properties. High tensile strengths with a simultaneously reduced weight can also be realized via sandwich sheets. Many applications require these sandwich sheets to be joined to other sheet parts or components. The joining methods that are frequently employed for sheets, for example fusion welding or soldering, cause problems, however, on account of their high heat input into the sandwich sheets. The thermoplastic layer usually used melts at least partially even in surrounding regions of the fastening or is damaged in some other way by the high heat input. In order to join a sandwich sheet to a further component, it is also possible to use a force-fitting and/or form-fitting joint, however, by using a fastening means, for example a screw or a rivet. However, it has been found that in the case of screwed joints or riveted joints, long-lasting firmness of these joints cannot be ensured on account of the creep behavior of the nonmetallic core layer, which generally consists of plastics material. The retaining force which the sandwich sheet has to provide with respect to the rivet or screw decreases on account of the creep behavior of the plastics material. As a result, or on account of the loss of the preloading force, the joint between the sandwich sheet and sheet or component loosens.